Turbine engines, and particularly gas or combustion turbine engines, are rotary engines that extract energy from a flow of combusted gases passing through the engine onto a multitude of turbine blades. Gas turbine engines have been used for land and nautical locomotion and power generation, but are most commonly used for aeronautical applications such as for aircraft, including helicopters. In aircraft, gas turbine engines are used for propulsion of the aircraft. In terrestrial applications, turbine engines are often used for power generation.
Gas turbine engines for aircraft are designed to operate at high temperatures to maximize engine efficiency, so cooling of certain engine components, such as the high pressure turbine and the low pressure turbine, may be necessary. Typically, cooling is accomplished by ducting cooler air from the high and/or low pressure compressors to the engine components which require cooling. Temperatures in the high pressure turbine are around 1000° C. to 2000° C. and the cooling air from the compressor is about 500° C. to 700° C. While the compressor air is a high temperature, it is cooler relative to the turbine air, and may be used to cool the turbine. When cooling the turbines, cooling air may be supplied to various turbine components, including the interior of the turbine blades and the turbine shroud.
Particles, such as dirt, dust, sand, and other environmental contaminants, in the cooling air can cause a loss of cooling and reduced operational time or “time-on-wing” for the aircraft environment. This problem is exacerbated in certain operating environments around the globe where turbine engines are exposed to significant amounts of airborne particles. Particles supplied to the turbine components can clog, obstruct, or coat the flow passages and surfaces of the components, which can reduce the lifespan of the components. Turbine shrouds can have particulate accumulation on backside cooling surfaces, causing reduction in part life. In some cases the entire cooling surface of the shroud becomes coated with particles, with the additional negative impact of film hole blockage.